The present disclosure relates to a fiber, a fiber aggregate, and an adhesive having the same, and more particularly, to a functional fiber and a fiber aggregate for realizing various functions, an adhesive for easily bonding electronic components, and a method for manufacturing the same.
An anisotropic conductive adhesive is a binder for simultaneously performing an electrical connection between electrodes by conductive particles and a mechanical connection by a thermosetting property of thermosetting resins based on thermosetting resins and conductive particles dispersed in the thermosetting resins.
A method of connecting electronic components using an anisotropic conductive adhesive is a lead free process which replaces a conventional soldering process. According to the method, a process is simple, environmentally friendly, and more thermally stable because it is unnecessary to momentarily apply high heat to products (low temperature process). In addition, manufacturing cost can be reduced because of using an inexpensive substrate such as a glass substrate or polyester flex, and it is possible to realize an ultrafine electrode pitch because electronic components are electrically connected by using fine conductive particles.
An anisotropic conductive adhesive having the above-mentioned merits is widely used for display packaging such as a smart card, a Liquid Crystal Display (LCD), a Plasma Display Panel (PDP) and a computer, a cell phone, a communication system, and the like.
One of the application fields where an anisotropic conductive adhesive is most commonly used is display module mounting. A market of an anisotropic conductive adhesive for an Outer Lead Bonding (OLB) used for connecting a flexible substrate to a glass substrate, and an anisotropic conductive adhesive for Printed Circuit Board (PCB) used for bonding a flexible substrate to a PCB is one of the fastest-growing markets.
Furthermore, the necessity of ultrafine pitch connection in Chip On Glass (COG) bonding of directly connecting a driver IC chip to a glass substrate and Chip On Film (COF) bonding of directly flip-chip connecting a driver IC chip to a flexible substrate becomes more important as a driver IC becomes highly integrated and complicated. Therefore, the importance of anisotropic conductive adhesive is also rapidly growing.
According to a technology of mounting electronic components using an anisotropic conductive adhesive, a thermocompression bonding process is basically used for completing connection by virtue of conduction due to conductive particles between electrode pads, and thermosetting of surrounding thermosetting resins.
During the thermocompression bonding process, conductive particles are moved due to flow of thermosetting resins included in an anisotropic conductive film. Therefore, a large amount of conductive particles should be used for preventing an electrical disconnection (hereinafter, referred as ‘open’ for simplicity), and conductive particles having a core-shell structure, where conductive particles are embedded by nonconductive materials, or a mixture of conductive particles and nonconductive particles should be used for preventing an electrical short (hereinafter, referred to as ‘short’ for simplicity).
As the necessity of ultrafine pitch connection is increased, the importance of technology for applying an electrical stability in vertical direction and electrical selectivity in X-Y direction without undesired electric current between electrodes is increased →.
FIG. 1 illustrates a related art method of connecting two electronic components using a related art anisotropic conductive film. In detail, as illustrated in FIG. 1A, according to a related art method for connecting two electronic components 10 and 30, after an anisotropic conductive film 20 containing a thermosetting polymer resin 22 and conductive metal particles 21 is attached on a surface of the electronic component 10 where an electrode 11 is formed, the electrode 11 is aligned with an electrode 31 of another electronic component 30. Then, heat and pressure are applied (thermally compressed) to thereby harden the thermosetting polymer resin 22 and electrically connect the two electrodes 11 and 31 to each other through the conductive particles 21.
However, according to such a related art method, as illustrated in FIG. 1B, the conductive particles 21 are ousted from an upper portion of the electrode 11 or 31 to the outside of the electrode 11 or 31 because the thermosetting polymer resin in the anisotropic film 20 flows during the thermocompression. This results in an electrical disconnection (region ‘A’ in FIG. 1B) between the electrodes 11 or 31, or an undesired short (region ‘B’ in FIG. 1B) between the electrodes.
For preventing an open between electrodes, excessive conductive particles should be used. Due to the excessive use of conductive particles, composite particles composed of a shell of nonconductive material and a core of conductive material should be used, or nonconductive particles should be used with conductive particles. However, even such a method cannot be a basic measure for preventing a short in fine pitch electrodes and for obtaining stable and selective electric connection, and requires high manufacturing cost. Thus, the related art method still has a limitation in connecting fine pitch electronic components using an anisotropic conductive film.